Action.

Muscle.

Origin.

Insertion.

Nerve-supply.

Depression

Digastric

Posterior belly from the digastric groove in front of the mastoid process. This ends in a tendon which is connected by a band of fascia to the body of the hyoid bone. The anterior belly arises from this, and is directed forwards and upwards

The oval impression on the lower border of the mandible close to the symphysis

Branch from inferior dental

Suprahyoid muscles - i.e., those which have their origins on the lower jaw, and are inserted in to the hyoid bone

Action.

Muscle.

Origin.

Insertion.

Nerve-supply.

Flexion

Depressors of the jaw when temporo-mandibular joint is fixed

Infrahypid muscles - i.e., between hyoid bone and sternum

Recti capitis antici major and minor, small muscles having their origins on the lesser cervical vertebrae and their insertions on the basilar process of the occipital bone

Extension

Sterno-mastoid

From the anterior surface of the manubrium sterni and the inner third of the upper border of the clavicle

The outer surface of the mastoid process and the superior curved line of the occipital bone

Spinal accessory

Splenius capitis

See Extension of Spinal Column

Com-plexus

See Extension of Spinal Column

Obliquus inferior

From the spine of the axis

The transverse process of the atlas

Post primary divisions

Rectus capitis posticus major and minor from the spine of the axis and atlas to the occipital bone be hind the foramen magnum

Action.

Muscle.

Origin.

Insertion.

Lateral flexion

Sterno-mastoid

See Extension

Splenius capitis

See Extension

Com-plexus

See Extension

Obliquus superior

From the transverse process of the atlas

The occipital bone beneath complexus

Rectus capitis lateralis, a small muscle in series with the other recti from the transverse process of the atlas to the occipital bone at the side of the foramen magnum

Rotation

Sterno-miastoid

Splenius capitis

Complexus

Recti capiti postici (major and minor)

'Obliqui (superior and inferior)